Since PEM fuel cells operate under

Since PEM fuel cells operate under relatively low temperature (< 100 C), the water vapor may condense to liquid water, especially at high current densities. While the existence of the liquid water keeps the membrane hydrated, it also blocks the gas diffusion passage, reduces the diffusion rate and the effective reacting surface area and hence the cell performance. To model the formation and transport of liquid water, ANSYS Fluent uses a saturation model based on [7] (p. 79), [5] (p. 79). In this approach, the liquid water formation and transport is governed by the following conservation equation for the volume fraction of liquid water, ❖, or the water saturation,